Young blood products: emerging treatment for Alzheimer's disease?

Alzheimer's disease is the most common neurodegenerative disorder and no disease-modifying treatment is currently available. Research has shown that while brain neurogenesis continues in adult life, it declines with age. Using parabiosis, plasma transfusions and direct administration of neural growth factors, animal studies have demonstrated the positive impact of exposure to young blood products on neurogenesis and synaptic plasticity in an aging brain. The hippocampus and the sub-ventricular zones were identified as the main regions affected. Promising findings have prompted researchers to experiment their effects in subjects with an established neurocognitive disorder, such as Alzheimer's disease. They argued that modification of brain vasculature, reactivation of adult neural stem cells, and remodeling of their synaptic activity/plasticity may lead to cognitive enhancement and increased neurogenesis. One pilot human study found that young donor plasma infusion protocols for adults with Alzheimer's disease were safe and feasible; however, no statistically significant improvements in cognition were detected. There is a need to conduct additional placebo-controlled human studies in larger samples. Future studies should focus on identifying an "optimal age" at which an intervention in humans may yield significant cognitive enhancement, as well as determining the types of transfusions with the best efficacy and tolerability profiles.